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package com.cosmos.util;

import java.math.BigInteger;
import java.util.UUID;

/**
 *
 * @author Miro
 */
public class NumberUtils
{
    public static byte[] toByteArray(short value)
    {
        return toByteArray(value, 2);
    }

    public static byte[] toByteArray(int value)
    {
        return toByteArray(value, 4);
    }

    public static byte[] toByteArray(long value)
    {
        return toByteArray(value, 8);
    }

    public static byte[] toByteArray(UUID uuid)
    {
        byte[] firstBytes = toByteArray(uuid.getMostSignificantBits());
        byte[] secondBytes = toByteArray(uuid.getLeastSignificantBits());
        return append(firstBytes, secondBytes);
    }

    private static byte[] toByteArray(long value, int length)
    {
        byte[] result = new byte[length];
        for(int i = 0; i < length; i++)
        {
            result[i] = (byte)(value & 0xFF);
            value >>>= 8;
        }

        return result;
    }

    /**
     * Appends two bytes array into one.
     *
     * @param a A byte[].
     * @param b A byte[].
     * @return A byte[].
     */
    public static byte[] append(byte[] a, byte[] b)
    {
        byte[] z = new byte[a.length + b.length];
        System.arraycopy(a, 0, z, 0, a.length);
        System.arraycopy(b, 0, z, a.length, b.length);
        return z;
    }

    public static short toShort(byte[] value)
    {
        return toShort(value, 0);
    }

    public static short toShort(byte[] value, int beginPos)
    {
        return (short)toNumber(value, beginPos, 2);
    }

    public static int toInt(byte[] value)
    {
        return toInt(value, 0);
    }

    public static int toInt(byte[] value, int beginPos)
    {
        return (int)toNumber(value, beginPos, 4);
    }

    public static long toLong(byte[] value)
    {
        return toLong(value, 0);
    }

    public static long toLong(byte[] value, int beginPos)
    {
        return toNumber(value, beginPos, 8);
    }

    private static long toNumber(byte[] value, int beginPos, int length)
    {
        if(value == null || value.length == 0)
            return 0;

        if(length > 8)
            length = 8;

        if((beginPos + length) > value.length)
            length = value.length - beginPos;

        if(length == 0)
            return 0;

        int endPos = beginPos + length;
        long result = 0;
        for(int i = (endPos - 1); i >= beginPos; i--)
        {
            int b = value[i] & 0xFF;
            result |= b;
            if(i > beginPos)
                result <<= 8;
        }

        return result;
    }

    public static UUID toUUID(byte[] value)
    {
        return toUUID(value, 0);
    }

    public static UUID toUUID(byte[] value, int beginPos)
    {
        if(value.length < beginPos + 16)
            throw new IllegalArgumentException("The length (" + value.length +
                    ") of bytes is less than required (" + beginPos + 16 + ").");

        long mostSigBits = toLong(value, beginPos);
        long leastSigBits = toLong(value, beginPos + 8);
        return new UUID(mostSigBits, leastSigBits);
    }

    public static UUID toUUID(BigInteger intValue)
    {
        return toUUID(intValue.toByteArray());
    }

    public static BigInteger toBigInteger(UUID uuid)
    {
        return new BigInteger(toByteArray(uuid));
    }

    public static void main(String[] args)
    {
        try
        {
            long l = 123456;
            System.out.println("l: " + l);
            byte[] ba = toByteArray(l);
            l = toLong(ba);
            System.out.println("l: " + l);

            l = -123456;
            System.out.println("l: " + l);
            ba = toByteArray(l);
            l = toLong(ba);
            System.out.println("l: " + l);

            int i = 123456;
            System.out.println("i: " + i);
            ba = toByteArray(i);
            i = toInt(ba);
            System.out.println("i: " + i);

            i = -123456;
            System.out.println("i: " + i);
            ba = toByteArray(i);
            i = toInt(ba);
            System.out.println("i: " + i);

            short s = 12345;
            System.out.println("s: " + s);
            ba = toByteArray(s);
            s = toShort(ba);
            System.out.println("s: " + s);

            s = -12345;
            System.out.println("s: " + s);
            ba = toByteArray(s);
            s = toShort(ba);
            System.out.println("s: " + s);

            UUID uuid1 = UUID.randomUUID();
            System.out.println("uuid1: " + uuid1);
            ba = toByteArray(uuid1);
            UUID uuid2 = toUUID(ba);
            System.out.println("uuid2: " + uuid2);
            System.out.println("uuid1.equals(uuid2): " + uuid1.equals(uuid2));

            BigInteger intValue1 = toBigInteger(uuid1);
            uuid2 = toUUID(intValue1);
            System.out.println("uuid1.equals(uuid2): " + uuid1.equals(uuid2));
            BigInteger intValue2 = toBigInteger(uuid2);
            System.out.println("intValue1.equals(intValue2): " + intValue1.equals(intValue2));
        }
        catch(Exception ex)
        {
            ex.printStackTrace();
        }
    }

}